A. Field of the Invention
The invention relates to a process for synthesizing alkylene bisdithiocarbamates or the ammonia adducts thereof starting from carbon disulfide, ammonia, a diamine and a metal oxide or the hydrate or hydroxide thereof. The invention also relates to mixtures which can be synthesized by the process. The product in question is mainly manganese ethylene bisdithiocarbamate, also known as "Maneb", and the ammonia adducts thereof.
B. Description of the Prior Art
Maneb and the ammonia-containing adducts of Maneb are known as fungicides. The synthesis of these compounds can be achieved by first reacting ethylenediamine with carbon disulfide and a strong base, e.g., sodium hydroxide, to obtain sodium bisethylenedithiocarbamate as described in U.S. Pat. No. 2,317,765. Aqueous solutions of such salts are then reacted with water-soluble manganese compounds, such as manganese sulfate or manganese chloride as described in U.S. Pat. No. 2,504,404. The water-insoluble manganese ethylene bisdithiocarbamate then precipitates out. By means of this process, Maneb is now being synthesized on an industrial scale.
In addition, West German Pat. No. 1,202,266 teaches a process for synthesizing ammonia-containing adducts of the manganese salt of ethylene bisdithiocarbamic acid, wherein a water-soluble salt, e.g., an ammonium salt of ethylene bisdithiocarbamic acid, is reacted with a water-soluble manganese salt, e.g., manganese sulfate, in the presence of ammonia. This patent also teaches that Maneb forms stable addition products with ammonia. They have much greater stability during storage than Maneb. Moreover, they have good fungicidal efficacy and better compatibility for plants than Maneb itself. A teaching of how the individual ammonia adducts having 1 or 2 ammonia molecules per manganese atom are synthesized is not given.
Finally, Austrian Pat. No. 195,440 teaches a process for synthesizing poorly water-soluble, crystalline ethylene bisdithiocarbamates of multivalent metals, wherein the metal oxide is allowed to react either with the necessary quantity of starting materials needed for the formation of ammonium dithiocarbamate or with an aqueous solution of ammonium ethylene bisdithiocarbamate. Of the metal oxides, only zinc oxide is specifically named. Also, in the examples, only zinc oxide is used for synthesizing zinc ethylene bisdithiocarbamate. No mention is made of ammonia adducts and the detailed synthesis thereof.